English : A modified 'standard' view of OpenStreetMap to reveal coverage worldwide on low zoom levels. Those (0–8) have essentially been created from scaling down tiles (slightly modified and without labels) of zoom level 9 and adding the labels afterwards. This experiment by Frederik Ramm can be viewed as a zoomable map (comparison via “+” on the right); more details of the technical approach.

English : The TIGER Battlegrid map shows colourful grid squares (orange for urban, green for countryside) for parts of the U.S. where more TIGER fixup work is needed by comparing with the newer TIGER 2012 data. Read more on this blog post